Debt left off of BK

There are a lot of important facts missing from your question. The first questions that should be answered are: Which Chapter of bankruptcy did you file?  If it was a Chapter 7 case, did the Trustee administer any assets?    If it was a Chapter 7 and no assets were administered (which is the case 95% of the time), and assuming you received your discharge, and the debt you state was left off was a dischargeable debt (for example,  a debt not incurred through fraud or a student loan, or recent tax debt), then the debt was discharged. In this case, even if it was your attorney's fault that the debt was omitted, there are no damages because the debt was discharged. If you filed a Chapter 13 or 11 case, or if your Chapter 7 case had assets administered, then the debt would not have been discharged.    Neither I nor anyone else on here can make a determination about whether this constitutes malpractice since I do not have all the facts as to why it was omitted.   However, you presumably signed your bankruptcy papers (under penalty of perjury) and, assuming the attorney provided you the papers to sign, the omission of the creditor is at least as much your fault as it is the attorney's.